Frameshift mutations in the bax gene are not involved in development of ovarian endometrioid carcinoma.

Abstract

The purpose of this study was to determine whether mutations in the Bax gene play a role in the development of ovarian endometrioid carcinoma with a microsatellite instability phenotype. We analyzed a total of 60 tumor specimens, 49 ovarian endometrioid carcinomas and 11 concurrent endometrial endometrioid carcinomas from 49 patients. Fourteen ovarian endometrioid carcinomas and 6 endometrial endometrioid carcinomas showed a microsatellite instability-high phenotype. Tumor and normal-tissue specimens from eight patients with a microsatellite instability-high phenotype colorectal carcinoma were included in this study as controls. The presence or absence of a mutation in the poly (G) 8 tract of the Bax gene was determined by polymerase chain reaction followed by direct DNA sequence analysis. A 1-base pair deletion at the poly (G) 8 tract and no expression of Bax and Bcl-2 proteins were identified in one microsatellite instability-high endometrial endometrioid carcinoma. Immunohistochemical staining for Bax and Bcl-2 proteins was negative on the tumor specimen that had this 1-base pair deletion. No mutations were found in the synchronous microsatellite instability-high ovarian endometrioid carcinoma from the same patient. In contrast, four (50%) of the eight microsatellite instability-high sporadic colorectal carcinomas had a mutation in the poly (G) 8 tract. Although Bax plays an important role in carcinogenesis of the colorectum with microsatellite instability-high phenotype, Bax may not play a direct role in the genesis of ovarian endometrioid carcinoma, regardless of microsatellite instability status.